Organophosphate / carbamate pesticides — biological monitoring

When to suspect: Pesticide mfg / formulation / packing, agricultural spraying, public-health vector control, godown fumigation.

Cholinesterase — RBC acetyl- (AChE) & plasma butyryl- (BuChE) (% of baseline)

Level	Interpretation
Baseline	≥ 2 pre-exposure baselines (after ≥ 30 days no exposure)
↓ 20–30%	Significant depression from that worker’s baseline — review / remove
↓ > 30–50%	Remove from exposure until recovery

No fixed BEI value — ACGIH "sampling time discretionary"; monitor % depression from the worker’s own baseline. (Urine dialkyl-phosphate metabolites are an alternate.)

Biological exposure index

ACGIH: cholinesterase, sampling time discretionary — interpret as % depression from the individual’s pre-exposure baseline (no single number).

Basis: ACGIH BEI (baseline-referenced); occupational-medicine practice.

Sample collection & preparation

Blood: RBC AChE in EDTA whole blood; plasma BuChE in heparin/serum — deliver promptly / keep cold (enzyme activity is labile).
Establish ≥ 2 baselines 3–14 days apart after ≥ 30 days unexposed; then monitor periodically + after exposure.
Disclose meds/conditions lowering plasma ChE (pregnancy, liver disease, recent succinylcholine).

Statutory basis. Factories Act 1948 sets only AIR limits (Second Schedule TWA/STEL, s.41F) and mandates the hazardous-process exam (s.41C, ≤12-monthly); it gives NO blood/urine values. The ranges below are ACGIH BEI / OSHA / clinical benchmarks (India has not adopted biological limits into law).

Reference information for occupational-health professionals — not medical advice, and not a substitute for examination by a qualified physician.

All 27 agents — toxicology & biological monitoring

MedFactory — Occupational Health Centre software for Indian factories